Re: [DistroKit] [PATCH 5/5] v8a: barebox: add a boot target for fastboot loaded image files

[Johannes Zink <j.zink@pengutronix.de>]

Hi Jan,

On 6/6/23 17:07, Jan Lübbe wrote:
> On Tue, 2023-06-06 at 16:47 +0200, Ahmad Fatoum wrote:
>> On 06.06.23 16:31, Johannes Zink wrote:
>>> This allows to boot a kernel with dtb and initrd entirely from RAM after
>>> loading it via Android Fastboot by simply calling 'boot fastboot'.
>>>
>>> Signed-off-by: Johannes Zink <j.zink@pengutronix.de>
>>> ---
>>>   configs/platform-v8a/barebox-common-defaultenv/boot/fastboot | 7 +++++++
>>>   1 file changed, 7 insertions(+)
>>>
>>> diff --git a/configs/platform-v8a/barebox-common-defaultenv/boot/fastboot b/configs/platform-v8a/barebox-common-defaultenv/boot/fastboot
>>> new file mode 100755
>>> index 000000000000..a06414d582bf
>>> --- /dev/null
>>> +++ b/configs/platform-v8a/barebox-common-defaultenv/boot/fastboot
>>> @@ -0,0 +1,7 @@
>>> +#!/bin/sh
>>> +
>>> +global.bootm.image=/tmp/kernel
>>> +global.bootm.initrd=/tmp/initramfs
>>> +global.bootm.oftree=/tmp/oftree
>>> +
>>> +global.linux.bootargs.dyn.root="rdinit=/sbin/init root=/dev/ram"
>>
>> Isn't rdinit=/sbin/init the default?
> 
> rd=/init is the defaut. root=/dev/ram is not needed, AFAIR, it's for initrd, not
> initramfs.

actually root=/dev/ram is needed, I found out the hard way, if it is missing 
the kernel complains it cannot mount a rootfs and will panic (though there 
might be a kernel config option to avoid this, I have not looked _too_ deep 
into it). Also, it is slightly different for v7a, where root=/dev/ram0 needs to 
be set instead of root=/dev/ram, so if there is a way to avoid this, I'd be 
happy to generalize things...

Johannes

> 
> Also, we could add a symlink /init -> /sbin/init, which would simplify using
> this initramfs with a bootloaders not passing the correct cmdline.
> 
> Jan

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